.bash_profile: line execution based on su vs. direct login.

[home user]

(Fedora-30)

good morning,

My .bash_profile looks like this:
---------------
# .bash_profile

# Get the aliases and functions
if [ -f ~/.bashrc ]; then
    . ~/.bashrc
fi

# User specific environment and startup programs

PATH=$PATH:$HOME/.local/bin:$HOME/bin
export PATH

ksysguard &

# the end.
---------------
But I want the KSysGuard to be launched only when:
* the session is interactive (not batch, cron, anacron, or at);
and
* it's a direct login from the login screen, not an "su" connection.
How do I do that in my .bash_profile?  That is,
-----
if [ what goes here? ]; then
    ksysguard &
fi
-----
How do I, within the .bash_profile if test, distinguish su connection 
vs. direct login from the login screen?

Bill.